Ethanoic acid was added to sodium bicarbonate solution and the gas evolved was tested with a burning splinter. The following four observations were reported

i) The gas burns with the pop sound and the flame gets extinguished

ii) The gas does not burn the splinter burns with a pop sound

iii) The flame extinguishes and the gas does not burn

iv) The gas burns with a blue flame and the splinter burns brightly.

The correct observation(s) is/are